Contact plug with flexible contact laminations



Dec. 6, 1949 s. G. ANDERSSON ET AL 2,490,632

CONTACT PLUG WITH FLEXIBLE CONTACT LAMINATIONS Filed Sept. 24, 1945P217211 elzznps 5 G. xizzdel 'ss 011/ I. E.fl.v.folaa.ncsaoz2,

Patented Dec. 6, 1949 UNITED STAT ES PATENT OFFICE I CoNTAoT PLUG WITHFLEXIBLE CONTACT LAMINATIONS Application September 24, 1945, Serial No.618,292

. In Sweden November 30, 1944 2 Claims. (01. 1734563) The presentinvention relates to a contact plug so formed that good contact alwaysis obtained when the plug is inserted into a Contact jack of the samedimensions as the plug, the construction thereby being such that greatmechanical stability is obtained.

A contact plug which is to be inserted into a jack without flexibleparts must always be flexible in itself in order to obtain perfectcontact against the inner walls of the jack. Such a contact pluggenerally consists of a round metal pin being slit in its longitudinaldirection in such a way that a pair of flexible contact surfaces areobtained. Such plugs are frequently used for strong current purposes butthey entail the inconvenience that the slit parts of the pin easily maybe broken and that the spring action in general is bad. Perfect contactwith a low, constant resistance is not always obtained whichparticularly for weak current purposes may be injurious. Manyconstructions of so-called banana plugs for weak current purposes areknown the inherent faults of which are more or less conspicuous. Contactbetween the inner walls of the jack and the conductor secured to thecontact plug is generally produced by flexible contact springs beingriveted to a centre pin in the contact prong which easily gives rise toa variable contact resistance. Most often also the mechanical stabilityleaves a great deal to be desired.

The contact plug according to the invention consists of a number ofoblong metal laminations arranged close to each other and of a widthmainly corresponding to the inner diameter of the contact jack intowhich the plug is to be inserted. They are further of suitable thicknessand provided with a slot in that part of the laminations intended to beinserted into the jack. In this way the disadvantages of the prongshitherto known are avoided at the same time as the plug may be formed insuch a way that it answers great claims from a mechanical point of view.One or more laminations are provided with a solderin lug orcorresponding contact device (set screw or the like) for connection of awire. The slit part of the laminations is of a width somewhat exceedingthe inner diameter of the jack, into which the plug is to be insertedand has a spring action in the plane of the lamination. A suitablecontact pressure may be produced by choice of the width of the plate oneach side of the slit. A great number of individual contactpossibilities are obtained since the plug is provided with a pluralityof laminations. Suflicient mechanical stability may be obtained as aplurality of laminations are arranged close to each other thus making itpossible to utilize the comparatively high moment of inertia of theflexible parts of each lamination. In order to obtain good mechanicalstability for forces perpendicular to the plane of the laminationstheassembly of laminations is arranged in a slot of a pin, the diameterof which is somewhat smaller than the diameter of the jack into whichthe contact plug is to be inserted. The diflerent parts are flxed to oneanother at the non-flexible parts of the laminations, for instance bysoldering, welding, by means of a metal ring, or the like. The contactdevice obtained in this way may as usual be provided with an insulatingbarrel.

The invention will be described more closely with reference to theannexed figures. Figs. 1c and 1b show contact laminations as seen fromabove and from the side. Fig. 2a shows an assembled contact plug andFigs. 2b and 20 a metal pin into which the laminations may be inserted.Each lamination in Figs. 1a and 1b consists of an oblong metal sheet Iprovided with a slot 3, two legs 2 thereby being formed on each side ofthe slot. The width of the lamination at the slot is as mentioned beforesomewhat wider than the inner diameter of the jack, into which the plugis to be inserted, the width otherwise being somewhat narrower than thisdiameter or at most equal to same. The laminations are in the embodimentshown provided with a soldering lug with a hole 5 for connection of aconductor. The lamination is further provided with a couple of stampings4 intended to keep the separate laminations in right position when theyare arranged close to each other as shown in Fig. 1b. The laminationsare inserted with their slit part into a metal pin 6 shown in Figs. 2band 2c in the slot indicated by I. By pressing a bushing 8 in Fig. 211over the metal pin and the laminations at the stampings 4 the difierentparts are rigidly fixed to one another. The slot 1 is of coursedimensioned so as to allow the laminations to have a spring actionalthough they can not be bent aside. The bushing 8 is in a common mannerprovided with an external thread by means of which it is kept in theinsulating barrel 9.

In such a plug a great number of individual Contact points are obtainedat the tongues 2 on the separate laminations which all are in directmetallic contact with a wire soldered to the lug. It has been provedthat perfect contact always is obtained evenwith very heavy oxidation ofthe contact surfaces produced in an artificial manner on account of thegreat number of small contact surfaces each having relatively highcontact pressure.

The construction of the contactv plug is in no Way limited to theembodiment above described. The laminations may be Welded or solderedtogether or in any other way connected to each.

other and it is of course not necessary to. provide the plug with themetal pin Bi Further it is not;

necessary that the slot 3 in the laminations'is made open at its oneedge in' order to obtain two, free legs 2. If some material is left'atthe edge-a greater stiffness is obtained attire-flexible parts of thelamination.

We claim:

1. In a contact plug adapted to be inserted-- in a jack socket, aplurality of elongatedmetal laminations arranged in, a juxtaposedrelationship, each of said laminations having a length- Wise slot in anend portion thereof, a metal pin of a smaller diameter than the widthofsaid-laminations, said pin having a slot therein receiving saidassembled laminations, and means: main-- taining unslotted end portionsof the laminationsin fixed relation to each other and in fixed relationto said pin;

2. In a contact plug adapted to'be inserted in a jack socket, aplurality of elongated metal 1aminations arranged in juxtaposedrelationship, each of said laminations having a lengthwise slot in anend portion thereof, a metal pin of a smaller diameter thanthe width ofsaid laminations, said pine having a slot therein receiving saidassembled laminations, and a bushing embracing the pin and unsiotted endportions of the laminations.

SVEN GUSTAV ANDERSSON. ERNST ELOF AKE J OI-IAN SSON.

REFERENCES CITED The. following references are of record in the fileofthis patent:

UNITED STATES PATENTS

